1. Field of the Invention
This invention relates generally to clamping devices. In a more specific sense, the invention relates to a clamping device adapted to be placed about a flexible, tubular member such as a fire hose, for the purpose of shutting off the flow of water therethrough.
2. Description of the Prior Art
Clamping device for fire hoses are well known in and of themselves. It often happens, for example, that a fire hose may extend a substantial distance from its coupling to a hydrant. In the use of the hose, a fireman controlling the hose at the nozzle end needs to have, in many instances, quick control over the flow. He may, for example, have to cut off the flow completely, while moving the hose or performing other duties. Then, it may be necessary that he start up the flow once again with equal speed and ease.
Typically, a hose connection is made between a hydrant and the inlet of a pump on the fire-fighting equipment. The pressure at the pump inlet is the relatively low hydrant pressure (e.g., 30 psi). The pump raises this to about 150 psi, typically in the hose extending from the pump outlet to the nozzle. It is in the high pressure portion of the hose that the cut-off clamp is used.
In some instances, cutting off the high pressure flow can be achieved by signaling the operator at the pump. This may be difficult, however, in some instances because of the distances involved, and because the operator at the pump may be out of view of the fireman working at the discharge end of the hose. Indeed, it may also be true that the pump may be left unattended for one reason or another.
Accordingly, it is desirable to use clamping devices, normally adjacent the discharge end of the hose, and these devices are typically of a readily portable character, so that they can be quickly placed in position about a hose, and used for the purpose of clamping off the hose to shut off the flow, for example when a hose ruptures or when a nozzle needs to be changed. Such clamping devices are so designed as to permit the flow to be resumed, with minimum loss of time, should this be necessary.
One of the main problems encountered, in the prior art, is to provide a jaw formation on the clamping device, that will be designated to effective shut off the flow through the fire hose under the application of mechanical or hydraulic pressure. The jaw formation is of extreme importance, because a fire hose can be, for example, approximately five inches in diameter, and exerts very heavy resistance to the clamping action.
It is also very important that the jaws be adapted for clamping off the hose without rupturing or otherwise damaging it. This presents a problem in light of the fact that the hoses are of fabric material and carry water at high pressure.
It is important, accordingly, to provide a clamping device that will have a jaw formation that is of particular effectiveness in shutting off flow through the fire hose upon the application of suitable pressure, which is normally exerted hydraulically by the provision of a hydraulic pump assembly incorporated in the clamp device.